In a year of really big home sales, one dwarfed the rest—and said a lot about the state of the real-estate market.

The Bowie-Sevier house—a Georgetown mansion that dates to the early 19th century—sold for $24 million, shattering the record for the most expensive home sale in DC by $10 million. Two of the city’s richest men struck this deal: Developer Herbert Miller sold the home to media entrepreneur Robert Allbritton.

Agent Mary Grover Ehrgood, who brokered the sale, says Washington’s ultra-high-end real-estate market is flourishing. This year, for example, eight sales broke the $7-million threshold in DC, six more than in 2006.

In 2005, AOL mogul Steve Case paid $24.5 million for Merrywood, the McLean childhood home of Jacqueline Kennedy Onassis.

A home can command top dollar, Ehrgood says, “when the buyer perceives that the property is ‘best in class.’ ” In addition to a prime location and estatelike site, this can mean historic significance, sweeping water views, or the imprint of a famous architect. Ehrgood says that in the very upper bracket, buyers also want grand rooms for entertaining.

As prices push higher, the definition of luxury is changing. Upscale amenities such as granite countertops and stainless-steel appliances have become commonplace. Two million dollars today may get you a very nice five-bedroom home in Chevy Chase or Great Falls, but nothing extravagant.

This year saw an explosion of high-end sales in Kalorama, the DC neighborhood next to Embassy Row. The area has been undervalued for years, Ehrgood says, and buyers can get more space for the money in Kalorama than in Georgetown.

Here are some of the year’s biggest deals involving boldface names:

Sellers: Real-estate developer Herb Miller and his wife, Patrice

Buyers: Media mogul Robert Allbritton and wife Elena, a dermatologist

Price: $24 million

Neighborhood: Georgetown.

The Millers—Herb developed Georgetown Park, Washington Harbour, and the Gallery Place complex next to Verizon Center—spent years restoring the seven-bedroom, 12-bath home (and eight-car garage) before selling it. Allbritton owns Channel 7 and NewsChannel 8 and publishes Politico.

Sellers: Stars of the “Plamegate” scandal, Joseph and Valerie Plame Wilson

Price: $1.8 million

Neighborhood: Foxhall, DC

Five bedrooms, views of the Washington Monument, library.

Buyers: Lobbyist Tony Podesta and his wife, Heather

Price: $3.9 million

Neighborhood: Kalorama, DC

Eight bedrooms, seven baths, pool, 12-zone stereo